NOT_SUPPORTED_MESSAGE

Method Detail

requestFusion

One should request either SYNC, ASYNC or ANY modes (never NONE)
and the implementor should return NONE, SYNC or ASYNC (never ANY).

For example, if a source supports only ASYNC fusion but
the intermediate operator supports only SYNC fuseable sources,
the operator may request SYNC fusion and the source can reject it via
NONE, thus the operator can return NONE as well to downstream and the
fusion doesn't happen.